Originally Posted by starchile
Oh, you scientific mind type folks!! Gotta love ya!
Well, thank you for all of your suggestions...I MAY have found the culprit. After disabling all of the notifications mentioned and STILL hearing that annoying sound...I just happened to be looking at my phone when the sound happened and noticed the refresh bars appeared. So, I went into my settings and looked around and found the "sync all" setting. I disabled auto sync and I haven't heard the sound since. I'm not 100% positive yet but I haven't heard the sound in a while. If I continue NOT to hear it, I'm going to turn the sync on again and listen for it to make sure.
THANKS FOR BEING HERE GUYS!!!
I quite enjoyed the mystery. When I was searching the device last night for what could be causing your invisible notifications, I ran across one option that might help you out.
My only other guess was going to be Google Talk. I recall someone in the past having phantom G-Chats happening in the background.
If you check in the Sound settings, there is a check box for disabling notifications for sync or newly refreshed feeds (something like that - don't have my phone with me). This is a new option in Sense 5 if I'm not mistaken. I think it was mostly added for BlinkFeed updates.